Television camera and white balance correcting method

ABSTRACT

The white balance of a television camera is not lost and kept properly even if the diaphragm is opened to the utmost limit at a dark place. A signal F representing the diaphragm value of the taking lens is inputted from an iris part  2  into a microcomputer  8 . The level adjusting values of the R, G, and B signals are set in the microcomputer  8  according to the diaphragm signal F and sent to a white balance correcting circuit  6 . The correcting circuit  6  adjusts the levels of the R, G, and B signals to the same value according to the level adjusting values.

FIELD OF THE INVENTION

The present invention relates to a television camera and a white balancecorrecting method and, more particularly, to a television camera inwhich the white balance is not lost and colors kept properly even if thediaphragm of the optical system of the camera is opened to the utmostlimit. The television camera includes not only its single unit, but alsoa unit in which the television camera and a recorder such as avideo-tape recorder are integrated in one-piece, and a unit in which thetelevision camera and a record/playback device such as a video-taperecorder are integrated in one-piece.

BACKGROUND OF THE INVENTION

In a television camera, respective levels of image signals for R, G andB channels corresponding to a white subject are adjusted to the samelevel, thereby keeping a white balance. This causes the white color tobe reproduced to a color in which the coloring is not lost and is notdifferent from that viewed by naked eyes, thereby improving the colorreproducibility of the whole screen, even if a light radiating thesubject is the sun light or an artificial light.

The correction of the white balance in conventional television camerashave been performed in the following manner. That is, a gain is adjustedso that the G signal level becomes the same level as the R signal andthe B signal levels by setting the diaphragm value at value at which theoptical properties of the taking lens become stable, for example, f 8.0,taking an image of a white subject on the whole screen, and performingthe white balance correction.

Now, taking lenses of recent television cameras have been improved inthe optical properties, and the signal processing technology has beenprogressed, so that most of them have the opening diaphragm value ofabout f 1.4, whereby they can take a subject even at a dark placebecause the range of the diaphragm spreads to opening side.

In cameras having the taking lens with such opening diaphragm value ofabout f 1.4, the white balance is successfully kept in a condition inwhich the diaphragm is closed in a manner that the diaphragm valueexhibits a value, for example, more than f 2.8.

However, when an image is taken by opening the diaphragm near to thelimit at which the diaphragm value exhibits a value less than f 2.8 in aplace short of illumination such as in door, even though the whitebalance adjustment has been performed, the whole screen may be short ofgreen color, or surplus of red color, so that the image may be coloredslightly with magenta color (for short of green color) or with red color(for surplus of red color) to cause the color reproducibility to bedecreased.

Hence, current situation is such that there has been made a selection ofeither one method in which an image is taken at a larger diaphragm valueby making up illumination at image taker side in a place short ofillumination, or that in which an image is taken by leaving the imagecolored slightly with magenta color or red color as it is.

Thus, the fact that, in image taking in a condition in which thediaphragm is opened neat to opening, the screen assumes magenta color orred color is because the trend of an increase in R, G and B signallevels associated with opening of the diaphragm becomes different nearthe diaphragm opening end so that G signal or R signal level becomesrelatively lower (G signal) or becomes relatively higher (R signal) thanother signal levels.

That is, as shown in the characteristic graph of FIG. 3, when openingthe diaphragm near to opening, associated with it, the image signallevel of the R, G and B channels obtained through a solid image sensordevice (commonly known as CCD) corresponding to a three-color separationoptical system and to respective colors increases, while in a regionwhere the diaphragm is relatively closed, the trend of an increase inthe R, G and B signals (each of which is an image signal) is uniform.

On the other hand, in a region where the diaphragm is largely opened andthe diaphragm value exhibits f 2.8 or less, the increasing trend variesamong the R, G and B signals such that for the G signal, its levelbecomes lower than that of other color signals, and for the R signal,its level higher than that of other color signals.

It is assumed that such characteristics are due to the way of how todeploy the light separated by a prism (where the G signal decreases) orto a variation in the light collecting characteristics of colors inrespective solid image sensor device (where the R signal increases), andsuch characteristics are unique to television cameras using the solidimage sensor device, or to three-tube, three-plate type cameras having acolor separation optical system such as prism.

In conventional white balance correcting method, taking a slightlyclosed diaphragm value such as f 8.0 as a reference, by level adjustingthe R, G and B signals under such certain diaphragm value, the whitebalance for the whole region of diaphragm is kept uniformly, therebyproviding a method neglecting the decrease of the G signal level or theincrease of the R signal level at the diaphragm opening end.

Hence, thereafter taking an image by opening the diaphragm near to thelimit causes the G signal or the R signal to tend to be decreased orincreased with respect to other signal levels, in spite of the whitebalance adjustment in advance, whereby the green color is short, or thered color is surplus, so that the image assumes magenta color or redcolor.

Therefore, it is an object of the present invention is to provide atelevision camera and a white balance correcting method wherein even ina condition in which the diaphragm is opened to the limit, the whitebalance is properly kept so that even in a place having a small quantityof light, an image having a good color reproducibility is obtained.

SUMMARY OF THE INVENTION

(1) A television camera of the present invention, which adjusts thelevel of the R, G and B signals obtained through a three-colorseparation optical system to keep the white balance, includes controlmeans for setting the level adjusting values of the R, G and B signalsaccording to the diaphragm signal indicating the diaphragm condition ofa taking lens, and white balance correction means for adjusting thelevels of the R, G and B signals according to the above-mentioned leveladjusting values, so that the level adjustment suited for the trend inthe increase of these signal levels associated with the opening of thediaphragm near to the limit is performed with respect to the R, G and Bsignals, and thus even in a condition in which the diaphragm is openedto the limit because of illumination being short, a proper white balancecorrection is performed.

In the television camera of the present invention, the level adjustingvalue in the above-mentioned control means is set at a value by whichthe level of one signal of either the G signal or the R signal isrelatively made even with that of other both signals. For example, inthe case where the diaphragm is opened beyond a predetermined limit, thelevel adjusting value is set at a value by which the level of one signalof either the G signal or the R signal is relatively increased ordecreased with respect to that of other both signals.

In such a case, although in general television cameras, due to thethree-color separation optical system and to the CCD construction, whenopening the diaphragm near to the opening end, there are indicatedcharacteristics in which the level of arbitrary signal (G signal, Rsignal, or the like) is decreased (in case of G signal) or increased (incase of R signal) relatively to that of other both signals (both R and Bsignals, and the like), by setting of the level adjusting value asmentioned above, the level adjustment is performed in a manner to makeup the gap among the R, G and B signals, whereby a white balance furtheradapted to an actual camera optical system is performed.

In the present invention, with the above-mentioned improved televisioncamera, setting of the level adjusting value in the control means andlevel adjusting according to the level adjusting value in the whitebalance correction circuit are performed in response to the change inthe diaphragm condition of the above-mentioned lens, whereby onlychanging the diaphragm causes the correction of the white balancematched with the diaphragm condition to be automatically performed.

(2) The white balance correcting method of the present invention is suchthat in keeping the white balance by adjusting the levels of the R, Gand B signals obtained through the three-color separation opticalsystem, the level adjusting values of the R, G and B signals are setaccording to the diaphragm condition of the taking lens, and then thelevels of the R, G and B signals are adjusted by the above-mentionedlevel adjusting value. The level adjustment suited for the trend in theincrease of these signal levels associated with the opening of thediaphragm near to the limit is performed with respect to the R, G and Bsignals, whereby even in a condition in which the diaphragm is opened tothe limit because of illumination being short, a proper white balancecorrection is performed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a white balance correcting device accordingto an embodiment of the present invention included in a televisioncamera.

FIG. 2 is a detailed diagram of the white balance correcting circuitshown in FIG. 1.

FIG. 3 is a characteristic graph of an image signal showing arelationship between the levels of the R, G and B signals obtainedthrough the three-color separation optical system from a white subjectand the diaphragm value.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to FIG. 1, the best mode of the present invention will beexplained in detail hereinafter. The present invention, though appliedto a broadcasting television camera to explain, is not limited to thetelevision camera for such application.

Referring to FIG. 1, a subject (not shown) is taken by a taking lens 1.A taking light passing through the taking lens 1 is inputted into aniris section 2. The iris section 2 adjusts an amount of light radiatedto the taking face of an image sensor device, which will be describedlater. A prism-type, three-color separation optical system 3 separatesthe taking light passing through the iris section 2 into three-colorlight components: red color (R), green color (G) and blue color (B).Although as another system of the three-color separation optical system,there are, for example, a dichroic mirror system and others, the presentinvention is not limited to these systems.

The three-color separation optical system 3, as well known, is acombination of three prisms 3 r, 3 g and 3 b, from which these threeprisms 3 r, 3 g and 3 b, a red-color light, a green-color light and ablue-color light are emitted, respectively. In this case, respectiveprisms 3 r, 3 g and 3 b are provided with a reflecting filter or atrimming filter of a dichroic film.

A solid image sensor device (CCD) 4 comprises an image sensor device 4 rfacing the prism 3 r for radiating the red-color light through the prism3 r from the taking face, an image sensor device 4 g facing the prism 3g for radiating the green-color light through the prism 3 g from thetaking face, and an image sensor device 4 b facing the prism 3 b forradiating the blue-color light through the prism 3 b from the takingface.

The image sensor devices 4 r, 4 g and 4 b process the red-color light,green-color light and blue-color light for an image radiated from theprisms 3 r, 3 g and 3 b to the R, G and B signals, respectively, andoutput them to an image signal processing circuit 5.

The image signal processing circuit 5 processes the R, G and B signalsfrom the image sensor devices 4 r, 4 g and 4 b for amplification and thelike, and then the R, G and B signals having been subjected to theprocessing of amplification and the like are encoded by an encoder 7into composite color image signals of NTSC system, PAL system, SECAMsystem or the like to be outputted.

Such an image signal processing circuit 5 contains a white balancecorrecting circuit 6. A microcomputer 8 acts as control means for whitebalance correction, and at the same time, performs various controlscorresponding to the operation contents of an operating section 9.

The iris section 2 performs the opening/closing operation of thediaphragm of the taking lens 1 according to the control from a diaphragmadjusting mechanism (not shown) for closing the aperture of the takinglens 1 to adjust the above-mentioned amount of light radiated, and atthe same time, outputs a signal indicating the opening condition of thediaphragm, that is, a diaphragm signal F to the microcomputer 8.

The white balance correcting circuit 6 in the image signal processingcircuit 5, as shown as an example in FIG. 2, comprises three analogmultipliers 6 r, 6 g and 6 b for multiplying individually the R, G and Bsignals, which have been outputted from the image sensor devices 4 r, 4g and 4 b and subjected to the processing of amplification and the like,by a coefficient to perform level adjustment. R, G and B designate theR, G and B signals before being corrected for white balance, and R′, G′and B′ designate the R, G and B signals after being corrected for whitebalance.

The microcomputer 8 adjusts multiplying coefficients Kr, Kg and Kb usedin the analog multipliers 6 r, 6 g and 6 b according to the datainputted from the iris section 2, and at the same time, inputs themultiplying coefficients thus adjusted to the analog multipliers 6 r, 6g and 6 b, thereby adjusting the levels of the R, G and B image signalsto correct the white balance.

More particularly, the microcomputer 8, as with the control unit ofconventional white balance correcting device, performs division of theimage region formed of the R, G and B signals, detection of the imageregion corresponding to a white subject, calculation of the levels ofthe R, G and B image signals in the image region, and the like, and inaddition to, stores the multiplying coefficients (level adjusting valueof the R, G and B signals) used in the analog multipliers 6 r, 6 g and 6b configuring the white balance correcting circuit 6, and supplies themto respective analog multipliers.

Further, the microcomputer 8 stores the multiplying coefficientssupplied to the white balance correcting circuit 6 by bringing them intocorrespondence with the whole of the diaphragm regions. The multiplyingcoefficients correspond to the adjusting value of the white balance, andhave been set by the white balance correcting operation previouslyperformed, and the multiplying coefficients corresponding to theadjusting value of the white balance have been stored in themicrocomputer 8.

Here, the adjusting value of the white balance set by the white balancecorrecting operation previously performed corresponds to the lensdiaphragm (e.g. general-purpose diaphragm value f 8.0) set at the timeof the white balance correcting operation, and thus does not correspondto all diaphragms in one-to-one correspondence. More specifically,opening the diaphragm near to the opening end (f 2.8 or lower) causes afixed white balance adjusting value to provide an insufficientcorrection. This is caused by the fact that, as explained in theabove-described FIG. 3, in the trend in the increase of signal levelassociated with the opening of the diaphragm, the G signal or the Rsignal is different from other signals. The different trend describedhere means, more specifically, for example, a trend in which the trendin the increase of the G signal becomes more gentle than that of the Rand B signals, or the trend in the increase of the R and B signalsbecomes more steep than that of G signal, or the trend in the increaseof the R signal becomes more steep than that of the G and B signals, orthe trend in the increase of the G and B signals becomes more gentlethan that of R signal.

Thus, the microcomputer 8, in a condition in which the diaphragm of thelens is not opened near to the opening end (or in which the diaphragm isclosed more than f 2.8), sets fixed multiplying coefficients to the R, Gand B signals according to the white balance correcting operationpreviously performed. On the other hand, in a condition in which thediaphragm of the lens is opened near to the opening end (or in which thediaphragm is opened beyond f 2.8), the following is performed.

That is, the microcomputer 8 makes slightly larger the multiplyingcoefficient for the G signal than that for both the R and B signals, andfurther in such a manner that the larger the diaphragm is opened, thelarger the degree of the relative increase in the multiplyingcoefficient is made. More specifically, the multiplying coefficient forthe G signal is set in such a manner that the signal level of the Gsignal is raised to that of both the R and B signals. Or, themultiplying coefficient for both the R and B signals is set in such amanner that the signal level of the R and B signals is lowered to thatof the G signal.

On the other hand, the microcomputer 8 also makes slightly smaller themultiplying coefficient for the R signal than that for both the G and Bsignals, and further in such a manner that the larger the diaphragm isopened, the smaller the degree of the relative decrease in themultiplying coefficient is made. More specifically, the multiplyingcoefficient for the R signal is set in such a manner that the signallevel of the R signal is lowered to that of both the G and B signals.Or, the multiplying coefficient for both the G and B signals is set insuch a manner that the signal level of the G and B signals is raised tothat of the R signal.

This improves the adjusting accuracy of the white balance which becomesunstable in the diaphragm region near the opening end. In addition to,this further improves the adjusting accuracy by varying the multiplyingcoefficient following the variation in the diaphragm in the diaphragmregion near the opening end. That is, although in the diaphragm regionnear the opening end, the white balance reacts sensitively to thevariation in the diaphragm to cause the correction to become furtherunstable, as described above, the white balance correcting accuracy inthe diaphragm region near the opening end is improved by varying themultiplying coefficient following the variation in the diaphragm in thediaphragm region near the opening end.

The microcomputer 8 stores in a form of table or numerical formula themultiplying coefficient corresponding to the white balance adjustingvalue, and in correspondence with the diaphragm signal F inputted fromthe iris section 2, outputs the multiplying coefficients for the R. Gand B signals corresponding to the diaphragm f. The multiplyingcoefficients are supplied through a D/A converter 11 to the whitebalance correcting circuit 6.

The white balance correcting circuit 6 changes the gain of the R, G andB signals according to the multiplying coefficients supplied from themicrocomputer 8, and adjusts the level of the R, G and B signals tobecome the same level. In fact, for example, the circuit 6 makes eventhe level of the G signal with that of both the R and B signals, or thelevel of the R signal with that of both the G and B signals. In thiscase, there may be set such that the level of the G signal or the Rsignal is caused to be increased or decreased, or that the level of theR and B signals or the G and B signals are caused to be decreased orincreased.

In the above-mentioned configuration, the image light from a subject isradiated from the lens 1 through the iris section 2, separated by thethree-color separation optical system 3 into three-color lights, redcolor, green color and blue color lights, which lights are radiated torespective image sensor devices 4 r, 4 g and 4 b. Then, outputted fromrespective image sensor devices 4 r, 4 g and 4 b are the R, G and Bsignals corresponding to the color lights, which R, G and B signals areinputted into the white balance correcting circuit 6.

The microcomputer 8 sets the white balance adjusting value (multiplyingcoefficient) according to the diaphragm signal F inputted from the irissection 2, and gives the value to the white balance correcting circuit6.

The white balance correcting circuit 6 adjusts the level of the R, G andB signals to become the same level according to the multiplyingcoefficients corresponding to the white balance adjustment given fromthe microcomputer 8, thereby keeping white balance. Even where thediaphragm is opened near to the opening limit because of illuminationbeing short, the G signal at a relatively low level or the R signal at arelatively high level is made even with the level of the R and B signalsor the G and B signals, so that the white balance is not lost.

A series of white balance correcting operations such as the setting ofthe level adjusting value at the microcomputer 8, and the leveladjusting at the white balance correcting circuit 6 according to theadjusting value may be performed in response to the change in thediaphragm signal F outputted from the iris section 2, or in response tothe instruction signal (inputted in the operating section 9 according tothe diaphragm set by the operator) from the operating section 9. Where aseries of white balance correcting operations are performed in responseto the change in the diaphragm signal F, only changing the diaphragmcauses the correction of the white balance matched with the diaphragmregion to be automatically performed.

Although in the form of the above-mentioned performance, the whitebalance correcting circuit is configured as an analog circuit, it willbe appreciated that white balance correcting means may be configured inthe microcomputer 8 in software.

Further, in the form of the above-mentioned performance, configurationhas been made such that the diaphragm signal F is outputted from theiris section 2. This is the most suitable configuration where thepresent invention is performed in a video recorder integral with camera.However, even in a configuration in which the white balance correctingdevice is separated from the lens section (e.g. where the white balancecorrecting device is separated from the video camera), the presentinvention can be embodied, and in the case, a signal indicating thediaphragm condition of the diaphragm is inputted from the outside to thewhite balance correcting device.

Also, although in the form of the above-mentioned performance, there hasbeen explained that the relative adjusting of the G signal and therelative adjusting of the R signal are separately performed, theexplanation is made for clarity, and it will be appreciated that theadjusting of both the signals is performed in complete harmony. Inessence, even when the degree of the diaphragm opening of the irissection varies, it is sufficient to adjust the level of both the signalsso that the white balance is kept at a good accuracy.

Further, although in the form of the above-mentioned performance, theconfiguration has been made in which the adjusting to make relativelyeven the level of the G signal with both the R and B signals, and theadjusting to make relatively even the level of the R signal with boththe G and B signals are simultaneously performed, it will be appreciatedthat only either of them may be preformed, and the configuration may bemade in which the adjusting to make relatively even the level of the Bsignal with both the R and G signals is also simultaneously performed.

INDUSTRIAL APPLICABILITY

With the present invention, the level adjusting of the R, G and Bsignals according to the degree of the diaphragm opening of the irissection is performed, and even in a condition in which the diaphragm isopened near to the limit, the levels of the R, G and B signals are madeeven to the same level, so that even when an image is taken by largelyopening the diaphragm in a place short of illumination, the whitebalance is not lost and an image having a good color reproducibility isobtained, whereby the television camera of the present invention issuitably utilized as the television camera for such image.

1. A television camera which adjusts levels of R, G, and B signalsobtained through a three-color separation optical system to maintainwhite balance, said television camera comprising: an iris section forperforming an opening/closing operation of a diaphragm of a taking lens,and outputting a diaphragm signal indicating an opening condition of thediaphragm; a microcomputer for inputting the diaphragm signal from theiris section, and setting level adjusting values of the R, G, and Bsignals; and white balance correcting means for adjusting levels of theR, G, and B signals according to the level adjusting values, whereinsaid white balance correcting means has three analog multipliers formultiplying individually the R, G, and B signals before being whitebalance corrected with multiplying coefficients thereto, and outputtingindividually the individually multiplied values as the R, G, and Bsignals after being white balance corrected, wherein said microcomputerstores the multiplying coefficients as said level adjusting values bybringing the multiplying coefficients into correspondence with a wholeof diaphragm regions of the taking lens, wherein in a condition in whichthe diaphragm of the taking lens is not opened near to an opening end,said microcomputer outputs said stored multiplying coefficients to saidanalog multipliers, wherein in a condition in which the diaphragm of thetaking lens is opened near to the opening end, said microcomputer setsindividually said multiplying coefficients in such a manner that a levelof at least one arbitrary signal of the R, G, and B signals is madesubstantially even to that of at least one of other R, G, and B signals,and outputs said individually set multiplying coefficients to saidanalog multipliers, wherein setting level adjusting values of the R, G,and B signals and level adjusting according to said setting areperformed in response to a change in the diaphragm condition of saidtaking lens, and wherein said at least one arbitrary signal is thesignal G.
 2. A television camera which adjusts levels of R, G, and Bsignals obtained through a three-color separation optical system tomaintain white balance, said television camera comprising: an irissection for performing an opening/closing operation of a diaphragm of ataking lens, and outputting a diaphragm signal indicating an openingcondition of the diaphragm; a microcomputer for inputting the diaphragmsignal from the iris section, and setting level adjusting values of theR, G, and B signals; and white balance correcting means for adjustinglevels of the R, G, and B signals according to the level adjustingvalues, wherein said white balance correcting means has three analogmultipliers for multiplying individually the R, G, and B signals beforebeing white balance corrected with multiplying coefficients thereto, andoutputting individually the individually multiplied values as the R, G,and B signals after being white balance corrected, wherein saidmicrocomputer stores the multiplying coefficients as said leveladjusting values by bringing the multiplying coefficients intocorrespondence with a whole of diaphragm regions of the taking lens,wherein in a condition in which the diaphragm of the taking lens is notopened near to an opening end, said microcomputer outputs said storedmultiplying coefficients to said analog multipliers, wherein in acondition in which the diaphragm of the taking lens is opened near tothe opening end, said microcomputer sets individually said multiplyingcoefficients in such a manner that a level of at least one arbitrarysignal of the R, G, and B signals is made substantially even to that ofat least one of other R, G, and B signals, and outputs said individuallyset multiplying coefficients to said analog multipliers, wherein settinglevel adjusting values of the R, G, and B signals and level adjustingaccording to said setting are performed in response to a change in thediaphragm condition of said taking lens, and wherein said at least onearbitrary signal is the signal R.
 3. A television camera which adjustslevels of R, G, and B signals obtained through a three-color separationoptical system to maintain white balance, said television cameracomprising: an iris section for performing an opening/closing operationof a diaphragm of a taking lens, and outputting a diaphragm signalindicating an opening condition of the diaphragm; a microcomputer forinputting the diaphragm signal from the iris section, and setting leveladjusting values of the R, G, and B signals; and white balancecorrecting means for adjusting levels of the R, G, and B signalsaccording to the level adjusting values, wherein said white balancecorrecting means has three analog multipliers for multiplyingindividually the R, G, and B signals before being white balancecorrected with multiplying coefficients thereto, and outputtingindividually the individually multiplied values as the R, G, and Bsignals after being white balance corrected, wherein said microcomputerstores the multiplying coefficients as said level adjusting values bybringing the multiplying coefficients into correspondence with a wholeof diaphragm regions of the taking lens, wherein in a condition in whichthe diaphragm of the taking lens is not opened near to an opening end,said microcomputer outputs said stored multiplying coefficients to saidanalog multipliers, wherein in a condition in which the diaphragm of thetaking lens is opened near to the opening end, said microcomputer setsindividually said multiplying coefficients in such a manner that a levelof at least one arbitrary signal of the R, G, and B signals is madesubstantially even to that of at least one of other R, G, and B signals,and outputs said individually set multiplying coefficients to saidanalog multipliers, wherein setting level adjusting values of the R, G,and B signals and level adjusting according to said setting areperformed in response to a change in the diaphragm condition of saidtaking lens, and wherein said at least one arbitrary signal is thesignal B.
 4. A television camera which adjusts levels of R, G, and Bsignals obtained through a three-color separation optical system tomaintain white balance, said television camera comprising: an irissection for performing an opening/closing operation of a diaphragm of ataking lens, and outputting a diaphragm signal indicating an openingcondition of the diaphragm; a microcomputer for inputting the diaphragmsignal from the iris section, and setting level adjusting values of theR, G, and B signals; and white balance correcting means for adjustinglevels of the R, G, and B signals according to the level adjustingvalues, wherein said white balance correcting means has three analogmultipliers for multiplying individually the R, G, and B signals beforebeing white balance corrected with multiplying coefficients thereto, andoutputting individually the individually multiplied values as the R, G,and B signals after being white balance corrected, wherein saidmicrocomputer stores the multiplying coefficients as said leveladjusting values by bringing the multiplying coefficients intocorrespondence with a whole of diaphragm regions of the taking lens,wherein in a condition in which the diaphragm of the taking lens is notopened near to an opening end, said microcomputer outputs said storedmultiplying coefficients to said analog multipliers, wherein in acondition in which the diaphragm of the taking lens is opened near tothe opening end, said microcomputer sets individually said multiplyingcoefficients in such a manner that a level of at least one arbitrarysignal of the R, G, and B signals is made substantially even to that ofat least one of other R, G, and B signals, and outputs said individuallyset multiplying coefficients to said analog multipliers, wherein settinglevel adjusting values of the R, G, and B signals and level adjustingaccording to said setting are performed in response to a change in thediaphragm condition of said taking lens.
 5. A television camera whichadjusts levels of R, G, and B signals obtained through a three-colorseparation optical system to maintain white balance, said televisioncamera comprising: an iris section for performing an opening/closingoperation of a diaphragm of a taking lens, and outputting a diaphragmsignal indicating an opening condition of the diaphragm; a microcomputerfor inputting the diaphragm signal from the iris section, and settinglevel adjusting values of the R, G, and B signals; and white balancecorrecting means for adjusting levels of the R, G, and B signalsaccording to the level adjusting values, wherein said white balancecorrecting means has three analog multipliers for multiplyingindividually the R, G, and B signals before being white balancecorrected with multiplying coefficients thereto, and outputtingindividually the individually multiplied values as the R, G, and Bsignals after being white balance corrected, wherein said microcomputerstores the multiplying coefficients as said level adjusting values bybringing the multiplying coefficients into correspondence with a wholeof diaphragm regions of the taking lens, wherein in a condition in whichthe diaphragm of the taking lens is not opened near to an opening end,said microcomputer outputs said stored multiplying coefficients to saidanalog multipliers, wherein in a condition in which the diaphragm of thetaking lens is opened near to the opening end, said microcomputer setsindividually said multiplying coefficients in such a manner that a levelof at least one arbitrary signal of the R, G, and B signals is madesubstantially even to that of at least one of other R, G, and B signals,and outputs said individually set multiplying coefficients to saidanalog multipliers.
 6. A television camera white balance correctingmethod for adjusting levels of R, G, and B signals obtained through athree-color separation optical system to maintain white balance, saidtelevision camera white balance correcting method comprising the stepsof: a) performing an opening/closing operation of a diaphragm of ataking lens, and outputting a diaphragm signal indicating an openingcondition of the diaphragm; b) inputting the diaphragm signal from thestep a) into a microcomputer, said microcomputer operative to set leveladjusting values of the R, G, and B signals; c) adjusting the levels ofthe R, G, and B signals according to the level adjusting values; d)multiplying individually the R, G, and B signals before being whitebalance corrected with multiplying coefficients thereto, and outputtingindividually the individually multiplied values as the R, G, and Bsignals after being white balance corrected; and e) storing themultiplying coefficients as said level adjusting values by bringing themultiplying coefficients into correspondence with a whole of diaphragmregions of the taking lens, wherein in a condition in which thediaphragm of the lens is not opened near to an opening end, saidmicrocomputer outputs said stored multiplying coefficients, and whereinin a condition in which the diaphragm of the lens is opened near to theopening end, said microcomputer sets individually said multiplyingcoefficients in such a manner that a level of at least one arbitrarysignal of the R, G, and B signals is made substantially even to that ofat least one of other R, G, and B signals.
 7. A television camera whitebalance correcting method for adjusting levels of R, G, and B signalsobtained through a three-color separation optical system to maintainwhite balance, said television camera white balance correcting methodcomprising the steps of: a) performing an opening/closing operation of adiaphragm of a taking lens, and outputting a diaphragm signal indicatingan opening condition of the diaphragm; b) inputting the diaphragm signalfrom the step a) into a microcomputer, said microcomputer operative toset level adjusting values of the R, G, and B signals; c) adjusting thelevels of the R, G, and B signals according to the level adjustingvalues; d) multiplying individually the R, G, and B signals before beingwhite balance corrected with multiplying coefficients thereto, andoutputting individually the individually multiplied values as the R, G,and B signals after being white balance corrected; and e) storing themultiplying coefficients as said level adjusting values by bringing themultiplying coefficients into correspondence with a whole of diaphragmregions of the taking lens, wherein in a condition in which thediaphragm of the lens is not opened near to an opening end, saidmicrocomputer outputs said stored multiplying coefficients, and whereinin a condition in which the diaphragm of the lens is opened near to theopening end, said microcomputer sets individually said multiplyingcoefficients in such a manner that a level of at least one arbitrarysignal of the R, G, and B signals is made substantially even to that ofat least one of other R, G, and B signals, wherein setting leveladjusting values of the R, G, and B signals and level adjustingaccording to said setting are performed in response to a change in thediaphragm condition of said taking lens, and wherein said at least onearbitrary signal is the signal G.
 8. A television camera white balancecorrecting method for adjusting levels of R, G, and B signals obtainedthrough a three-color separation optical system to maintain whitebalance, said television camera white balance correcting methodcomprising the steps of: a) performing an opening/closing operation of adiaphragm of a taking lens, and outputting a diaphragm signal indicatingan opening condition of the diaphragm; b) inputting the diaphragm signalfrom the step a) into a microcomputer, said microcomputer operative toset level adjusting values of the R, G, and B signals; c) adjusting thelevels of the R, G, and B signals according to the level adjustingvalues; d) multiplying individually the R, G, and B signals before beingwhite balance corrected with multiplying coefficients thereto, andoutputting individually the individually multiplied values as the R, G,and B signals after being white balance corrected; and e) storing themultiplying coefficients as said level adjusting values by bringing themultiplying coefficients into correspondence with a whole of diaphragmregions of the taking lens, wherein in a condition in which thediaphragm of the lens is not opened near to an opening end, saidmicrocomputer outputs said stored multiplying coefficients, and whereinin a condition in which the diaphragm of the lens is opened near to theopening end, said microcomputer sets individually said multiplyingcoefficients in such a manner that a level of at least one arbitrarysignal of the R, G, and B signals is made substantially even to that ofat least one of other R, G, and B signals, wherein setting leveladjusting values of the R, G, and B signals and level adjustingaccording to said setting are performed in response to a change in thediaphragm condition of said taking lens, and wherein said at least onearbitrary signal is the signal R.
 9. A television camera white balancecorrecting method for adjusting levels of R, G, and B signals obtainedthrough a three-color separation optical system to maintain whitebalance, said television camera white balance correcting methodcomprising the steps of: a) performing an opening/closing operation of adiaphragm of a taking lens, and outputting a diaphragm signal indicatingan opening condition of the diaphragm; b) inputting the diaphragm signalfrom the step a) into a microcomputer, said microcomputer operative toset level adjusting values of the R, G, and B signals; c) adjusting thelevels of the R, G, and B signals according to the level adjustingvalues; d) multiplying individually the R, G, and B signals before beingwhite balance corrected with multiplying coefficients thereto, andoutputting individually the individually multiplied values as the R, G,and B signals after being white balance corrected; and e) storing themultiplying coefficients as said level adjusting values by bringing themultiplying coefficients into correspondence with a whole of diaphragmregions of the taking lens, wherein in a condition in which thediaphragm of the lens is not opened near to an opening end, saidmicrocomputer outputs said stored multiplying coefficients, and whereinin a condition in which the diaphragm of the lens is opened near to theopening end, said microcomputer sets individually said multiplyingcoefficients in such a manner that a level of at least one arbitrarysignal of the R, G, and B signals is made substantially even to that ofat least one of other R, G, and B signals, wherein setting leveladjusting values of the R, G, and B signals and level adjustingaccording to said setting are performed in response to a change in thediaphragm condition of said taking lens, and wherein said at least onearbitrary signal is the signal B.
 10. A television camera white balancecorrecting method for adjusting levels of R, G, and B signals obtainedthrough a three-color separation optical system to maintain whitebalance, said television camera white balance correcting methodcomprising the steps of: a) performing an opening/closing operation of adiaphragm of a taking lens, and outputting a diaphragm signal indicatingan opening condition of the diaphragm; b) inputting the diaphragm signalfrom the step a) into a microcomputer, said microcomputer operative toset level adjusting values of the R, G, and B signals; c) adjusting thelevels of the R, G, and B signals according to the level adjustingvalues; d) multiplying individually the R, G, and B signals before beingwhite balance corrected with multiplying coefficients thereto, andoutputting individually the individually multiplied values as the R, G,and B signals after being white balance corrected; and e) storing themultiplying coefficients as said level adjusting values by bringing themultiplying coefficients into correspondence with a whole of diaphragmregions of the taking lens, wherein in a condition in which thediaphragm of the lens is not opened near to an opening end, saidmicrocomputer outputs said stored multiplying coefficients, and whereinin a condition in which the diaphragm of the lens is opened near to theopening end, said microcomputer sets individually said multiplyingcoefficients in such a manner that a level of at least one arbitrarysignal of the R, G, and B signals is made substantially even to that ofat least one of other R, G, and B signals, wherein setting leveladjusting values of the R, G, and B signals and level adjustingaccording to said setting are performed in response to a change in thediaphragm condition of said taking lens.